Hello all, I was wondering if there are any experiences or discussions on using 'GPU style shaders' in raytracing.I was thinking to try to use SSAO (screen space ambient occlusion) in my CPU raytracing.

SSAO is computed in a fragment shader. You will have to pass a depth buffer texture to the shader. A depth buffer is fairly simple to generate as a ray tracing result, you basically just store first hit positions in world/object space and later transform them to OpenGL window coordinates.

I wouldn't consider such a rendering pass part of the ray tracing pipeline, but rather a post processing step, similar to the compositing step you perform when you render geometry e.g. from both ray tracing and OpenGL in a single frame.

If you treat it as such - a post processing step that is independent from ray tracing and implemented with shaders - yes, this is applicable to a GPU ray tracer. Say you do direct rendering, you will unmap/unbind the rendering PBO in your compute context, and pass it over to the OpenGL/DirectX realm for further processing.

Shaders in general are entry points to a fixed function pipeline. The ray tracing pipeline differs from the rasterization pipeline, thus I would expect other types of "shaders", e.g. ones that determine how a ray is treated that just left the scene (a "miss" program/shader). Have a look at Nvidia Optix for such an approach.